Understandable to many a listener (5)
I believe the answer is:
clear
'understandable' is the definition.
(similar in meaning)
'many a listener' is the wordplay.
'many a' becomes 'cl' (I can't justify this - if you can you should give a lot more credence to this answer).
'listener' becomes 'ear' (body part which hears or listens).
'cl'+'ear'='CLEAR'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for clear that I've seen before include "Open; not cloudy" , "Plainly" , "negotiate" , "Exculpate" , "Fair - innocent" .)